International Poplar Commission 24th Session, Dehradun, India
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International Poplar Commission
24th Session, Dehradun, India
COUNTRY REPORT
Activities Related to Poplar and Willow Cultivation and Utilization
Electronic versions of national reports (including the questionnaire) should be sent to the IPC-
Secretariat, E-mail IPC-Secretariat@fao.org no later than 31st March 2012.
The reporting period is 2008 to 2011 (4 years).
I. POLICY AND LEGAL FRAMEWORK
In Itay poplar and willow cultivation is traditionally considerated much more related to agriculture
than to forestry. The first main reason is the existence of a strict forest legislation not allowing to
turn into agriculture land that has been covered by forest (national law n. 3267 of the year 1923,
taken into account also by the last forest law, the decree n.227 of 2001). The relevant protective
functions towards soil erosion, landslides prevention and water management carried out by forests
in Italy stay behind this provision, aiming to avoid land covered by forest from being converted
into other uses, for instance agricultural and urban ones: therefore poplar plantations, due to their
flexible and short-term management, are still considered as an agricultural crop to not incurr in
such constraints. The second reason is that poplar cultivation is feasible mainly on plane, flat soils
managed in an integrated way by agriculture farms, also benefiting sometimes of EU subsidies
provided by the rural development regulation addressed to agricultural activities.
Laying in a sort of “limbo” between agriculture and forestry, poplars and willows’ cultivation is
not regulated by any specific national policy, apart from few actions promoted mainly by the
National Poplar Commission of Italy and by some interested Regions (e.g. Regione Lombardia).
During last years no any significant development in national policies, laws or regulations related to
poplars or willows did occurr, apart from the definition of “forest” of the decree 227/2001
currently under revision. In the meantine the surface covered by traditional poplar cultivations is
continuously decreasing because the competition, both in the use of soil with other more rentable
agricultural crops and because cheaper poplar products coming from abroad: such surface so
reached in 2005 an amount estimated around 66.000 ha and it is probably still further decreasing.
Neverthless, many interesting developments are occurring in research and field activities, mainly
in relation to innovative uses of poplars. Many centres – for instance the Research Unit of Casale
Monferrato, some Universities and private forest nurseries - are currently carrying out selections
and experiments on new clones having characteristics of salinity, drought and pests resistance. The
interest in the use of poplars and other fast growing species (as elms) cultivated in fast growing
plantations is also continuosly increasing, in many cases combining the goals of bioenergy
production and phytoremediation of polluted waters and soils: the surface of short rotation
plantations is therefore raising, although it is not yet fully captured by official statistics.
In some cases wood products from poplars or others plantations start to be used in big plants for
biorefinery (a 40 ktpa cellulosic ethanol plant is about to start its activities in Crescentino – VC
and it is expected to absorb some 80% of the poplar production in Piedmont) or for processing
new wood products (e.g. OSB poplar boards whose first factory is about to be completed inConiolo - AL), therefore likely to increase the economic competition in the use of poplars
products. Also different cultivations systems - for instance a 15 years harvesting period combined
with a mixed composition of poplars and others - is currently promoted in Lombardia together
with a growing interest to consider in the carbon storage capacities of poplar stands. Also their
possible environmental outputs, expecially in urban and periurban areas, are taken into account in
new forests planted for recreational purposes. Some details on such researches are given below.
II. SUMMARY STATISTICS (Questionnaire)
Complete the attached questionnaire on poplars and willows summarizing statistics of key
parameters in poplar and willow resources, production, utilization, trade and future trends.
The statistical data reported in the "Questionnaire" derive from the national forest inventory
INFC (INFC, 2005), available since 2007. Indigenous Poplars and Willows amount to 58.223
hectares, including mainly P. nigra, P. alba and S. alba. Planted poplars cover 101.430
hectares (Questionnaire tab.1) taking into account intensive plantations (66.269 ha), semi-
natural forests (29.161 ha) and short rotation forestry (about 6.000 ha). Planted poplars
represent 60 % of all poplar and willow categories, among which 40% are intensive plantations
for the production of wood for the wood processing industry (Questionnaire tab. 2). The most
cultivated clone among planted Poplars is ‘I-214’ (77%) (Questionnaire tab. 3).
No information is available on the productions of the ‘Indigenous’ category. ‘Fuelwood chips’
include fuelwood originating both from intensive plantations and from energy SRF
(Questionnaire tab. 5).
III. TECHNICAL INFORMATION
1. Identification, registration and varietal control
Report on accomplishments on identification and on proposals made for the registration of
new cultivars of poplars and willows.
During the last four years the National Poplar Commission of Italy registered definitively n. 17
poplar clones in the National Register of Forest Basic Materials (NRFBM) according to articles
n.10 and n.11 of the Legislative Decree n. 386/2003 (Table 1). Most of these clones were selected
at the CRA-PLF research center of Casale Monferrato (AL): ‘Soligo’, ‘Lambro’, ‘Taro’,
‘Brenta’, ‘Mella’, ‘Timavo’, ‘Arno’, ‘Lima’, ‘Adda’, ‘Stura’, ‘Panaro’, ‘Oglio’, ‘Sile’. The
others belong to private owners or private companies : ‘Ballottino’ was selected by Mr.
Fabrizio Di Tella, ‘Patrizia Invernizzi’ by Ms. Patrizia and Maria Invernizzi (Gussola, CR),
‘A4A’ by Mr. Franco Alasia (Cavallermaggiore, CN).
Other n.9 clones obtained temporary (10 years) registration in the NRFBM (Table 2). Most of
them – ‘Sirio’, ‘Pegaso’, ‘Monviso’, ‘AF2’, ‘AF6’, ‘AF8’ - were selected by the Alasia Franco
Company; the remaining ones, ‘Imola’ and ‘Orion’, belong to the CRA-PLF. For two P. alba
clones selected by Mr. F. Alasia for biomass purposes, ‘Marte’ and ‘Saturno’, the phase of
temporary registration expired in 2011 and they will soon be registered definitively. Moreover
there are n. 11 poplar clones still under test (Table 3); among these, the clones ‘AF3’ and
2‘Baldo’ will be temporarily registered and commercialized for the period 2012-2022.
Concerning Salix spp., recent releases specifically targeted for biomass production are the two
varieties ‘Drago’ and ‘Levante’ (seedlings from an open pollinated S. matsudana female)
Table 1 - Poplar clones definitively registered in the National Register of Forest Basic
Materials
Clone Registration Sex Species Breeder
request definitive
SOLIGO 1991 01/07/2011 M Populus spp. CRA-PLF
LAMBRO 1991 01/07/2011 M Populus spp. CRA-PLF
TARO 1991 01/07/2011 M Populus spp. CRA-PLF
BRENTA 1991 01/07/2011 F P. ×canadensis CRA-PLF
MELLA 1991 01/07/2011 F P. ×canadensis CRA-PLF
TIMAVO 1992 01/07/2011 M P. ×canadensis CRA-PLF
ARNO 1992 01/07/2011 M P. ×canadensis CRA-PLF
LIMA 1992 01/07/2011 F P. ×canadensis CRA-PLF
ADDA 1997 01/07/2011 F P. ×canadensis CRA-PLF
STURA 1997 01/07/2011 F Populus spp. CRA-PLF
SESIA 1997 01/07/2011 F P. ×canadensis CRA-PLF
PANARO 1997 01/07/2011 M P. ×canadensis CRA-PLF
OGLIO 1997 01/07/2011 M P. deltoides CRA-PLF
SILE 1997 01/07/2011 F Populus spp. CRA-PLF
A4A 1995 01/07/2011 F P. ×canadensis Alasia Company
BALLOTTINO 1995 01/07/2011 F P. ×canadensis F. Di Tella
PATRIZIA 1991 01/07/2011 F P. ×canadensis P. Invernizzi
INVERNIZZI
Table 2 - Poplar clones temporarily registered in the National Register of Forest Basic
Materials
Clone Registration Sex Species Breeder
request temporary
IMOLA 2002 01/07/2011 F P. ×canadensis CRA-PLF
ORION 2002 01/07/2011 M P. ×canadensis CRA-PLF
SIRIO 2003 01/07/2011 M P. ×canadensis Alasia Company
MONVISO 2003 01/07/2011 F P. ×canadensis Alasia Company
PEGASO 2000 01/07/2011 M Populus spp. Alasia Company
AF2 2003 01/07/2011 M P. ×canadensis Alasia Company
AF6 2005 01/07/2011 F Populus spp. Alasia Company
AF7 2005 01/07/2011 M Populus spp. Alasia Company
3AF8 2005 01/07/2011 F Populus spp. Alasia Company
MARTE 1999 30/03/2001 M Populus alba Alasia Company
SATURNO 1999 30/03/2001 M Populus alba Alasia Company
Table 3 - Poplar clones submitted to the National Poplar Commission
Clone Date of Status Sex Species Breeder
request
AF3 2005 testing F/M Populus spp. Alasia Company
AF4 2005 testing F P. ×canadensis Alasia Company
AF9 2005 testing ? Populus spp. Alasia Company
DIVA (83.002.031) 2005 testing F P. ×canadensis CRA-PLF
ALERAMO (83.141.020) 2002 testing M P. ×canadensis CRA-PLF
TUCANO (84.260.003) 2002 testing M P. ×canadensis CRA-PLF
83.002.011 2002 testing F P. ×canadensis CRA-PLF
83.141.017 2002 testing M P. ×canadensis CRA-PLF
83.190.012 2002 testing M P. ×canadensis CRA-PLF
84.048.032 2002 testing M P. ×canadensis CRA-PLF
BALDO (85.036) 2011 testing M P. deltoides CRA-PLF
2. Production Systems and Cultivation
Report separately information on the application of new knowledge, technology and
techniques in application of poplar and willow culture for different purposes, including
production, protection or conservation:
(a) Nursery practices and propagation techniques including applications of
biotechnology - particularly plant propagation, reproductive materials, use of
GMOs etc.
In the last four years the Research Unit for Intensive Wood Production of the CRA in Casale
Monferrato has been working on adapting the cultural model to the new clones recently
registered in the National Register of Basic Forest Materials. In particular pruning trials are in
progress, which are conducted in the nursery at the beginning of the second year, to reduce the
dimensions of knots and the tapering shape of the poles.
New plant densities have been tested in the stoolbed for the production of cuttings of the new
clones - 67.000 plants per hectare instead of 55.000 - to try and reduce above all the
dimensions of the whips and the number of silleptic branches after each coppicing.
Technical advice has been provided to private nurserymen for the introduction of drip
irrigation as an alternative to sprinklers to reduce water consumption in nurseries.
(b) Planted Forests with emphasis on the experiences and experiments concerning
the purpose, choice and preparation of site, the choice of cultivars, type of
plants, spacing and layout of plantations; planting and tending (fertilization,
4irrigation, weeding, pruning, etc.); management (growth, rotation in relation to
yields and industrial requirements, thinning techniques if practised, etc).
The area of traditional poplar cultivation, based on ten-year cycles, for the production of
plywood, is steadily decreasing. The tendency is also continuing towards a farming model
based on increased distances between plants, with a density of about 240 plants per hectare
instead of the 280-330 previously used to produce logs of higher quality and to have greater
flexibility in the length of the cycle.
Poplar cultivation is probably undergoing a differentiation process towards a number of
diverse cultural models, each specific to a group of products or environmental services (e.g.
phytoremediation, especially in combination with SRF, and landscape restoration). In the short
run the demand for poplar wood by pallet, paper and energy industries is likely to increase.
Such demand will no longer be satisfied only by the sub-products of traditional poplar
cultivation, therefore dedicated cultivations will become necessary.
Research activities on these topics have been supported by ministerial funding with the goal to
obtain technical and economic information, to increase dry matter production per hectare and
to achieve the objectives defined in the national strategy for rural biomass energy development.
In this framework, 60 experimental plantations have been established all over the Country
under different environmental conditions applying either the “Very high density model” (5700-
10000 plants per hectare) or the “High density model” (1100-1600 plants per hectare) and
using poplar, willow, and other fast growing species.
The new poplar varieties ‘Orion’, ‘Imola’, ‘Baldo’ selected at the CRA-PLF and ‘Monviso’,
‘AF2’, ‘Sirio’, ‘Pegaso’, ‘AF8’ selected by the Alasia Franco Company, characterized by good
growth rate, disease and pest tolerance and better sprouting ability after repeated coppicing,
have determined an increase of productions while reducing the economic and energetic costs.
Site characteristic (soil fertility, climatic condition) and water availability (precipitation and
irrigation) are the main limiting factors to productivity. The clones/provenances utilized in
SRC trials have showed yields up to 25 Oven Dry tons (O.D.t.) ha-1year-1; the yields in
commercial plantations, where fertilization and irrigation are rarely applied by farmers, have
been lower (average ranging from 6 to12 O.D.t ha-1year-1).
In the “very high planting density” trials the coppice cycle is generally short (2-3 years); the
quality of the wood biomass produced is low owing to a high bark percentage (15-20%) and it
is mostly used as chips for bio-energy power plants or for co-firing in thermo-electric plants
and incinerators. In the case of “high planting density” the cycle is longer (5-6 years) and
usually the yields obtained are within the range of 8 to 20 O.D.t ha-1year-1; in this case the
quality of the raw material is good, having a lower bark percentage, and it is preferably used
for other industrial products or for pellet production.
According to these preliminary results recently planted SRC show to be a good renewable
energy source, although further research could improve the cultivation of dedicated woody
crops. Further developments of woody bio-energy crops will be connected to the
implementation of the 5-6 years rotation model, along with improved cultivation techniques, or
5associated with phytoremediation, as well as to enlarging the choice of clone/species suitable
to different site conditions, especially in central and southern parts of the Country.
(c) Indigenous Forests, with emphasis on experiences and experiments concerning
silvicultural treatments, harvesting, management, protection and regenerating of
natural forests.
Within a research project funded by the Po River Fluvial Park, environmental analyses were
carried out in the northern plains of Italy to characterize suitable sites to be converted into
semi-natural forests. An old poplar plantation and an old natural plain forest located in a
typical flooding area, 16 hectares wide, nearby Casale Monferrato were chosen to the purpose.
In order to evaluate the ecological conditions and to choose both the silvicultural practices to be
carried out on the indigenous forest and the composition and the layout of the area to be converted
into a semi-natural forest, the Soil Quality Index, based on the arthropods present in the top soil,
was calculated. Such index ranges from 0 to about 300, where 0 indicates the worse quality soil
whilst the maximum value corresponds to the best quality soil, typical of natural forest. The
soil was alluvial with sandy or coarse sandy texture. The area to be turned into a semi-natural
forest was covered by an over-mature artificial poplar stand with many defective trees. The
natural forest surrounding this plantation mainly consisted of Populus nigra, Populus alba,
Salix alba, Quercus robur, Crataegus monogyna, all of which quite degraded due to the
presence of Robinia pseudacacia. The Soil Quality Index reached the highest value (206) in
the old poplar plantation where the tree crowns were totally closed; in the natural forest it was
180, while in the poplar plantation where many trees were missing it only reached 122.
To convert the artificial plantation as rapidly as possible, with only few cultural operations, the
old stand was felled and a semi-natural plantation was established using Populus nigra and
Populus alba as pioneer species, beside other forest species like Quercus robur and Crataegus
monogyna.
As for poplars, the planting material was provided by the nursery of the CRA-PLF
experimental farm, where over 170 genotypes collected from the northern regions of Italy are
produced for environmental purposes. Poplars were planted at 8 m x 8 m spacings, with the
other species in between, with a semicircular layout following the old river meander. Hydrogel
(Potassium polyacrylammide) was mixed with the soil in the holes before planting to ensure
water availability during the drought period. Weed control was carried out twice a year with a
shredder.
This activity resulted in a dynamic poplar stand, which was an in situ genetic conservation unit
able to assure adaptation to climate changes and to facilitate natural dissemination and river
banks re-colonization.
(d) Agroforestry and Trees Outside Forests with emphasis on the experiences, studies
and experiments in different growing mechanisms for trees outside forests and
agroforestry systems and their effects on forest and agricultural crops or livestock
and diversification of the landscape.
Poplars and willows are typical features of the Italian rural landscape, mainly in Northern Italy (Po
6Valley). They are present as forest plantations, tree rows, riparian strips and in some agroforestry
systems.
In the latter case poplar trees (200-333 trees/ha) are grown in combination with herbaceous crops
(corn, soy, horticultural and fodder crops) during the first 2-3 years of a 10 year rotation. In the
past, poplars were often grown in association with cereal crops (wheat and barley), in Piedmont.
This practice is advantageous with heavy soils, where in spring the water consumption of
herbaceous crops improves the soil aeration and the development of poplar roots; on the contrary,
on loose soils or in dry years this intercropping could hinder the development of poplar seedlings.
More generally, agroforestry systems can reduce the contamination of groundwater by nitrate
leaching. Poplar roots, in fact, which are deeper than herbaceous ones, play a complementary role
in nitrate adsorption.
Poplars and willows are also present as Trees Outside Forest, generally as tree rows and riparian
strips (called hedgerows in the following), mostly represented by Populus nigra, P. alba, P. x
canadensis and Salix spp. Although specific research projects, integrated with the 2nd Italian forest
inventory (INFC), provided national estimates of the area and of some qualitative attributes of
hedgerows, an estimate of the area covered by poplar and willow hedgerows is not available at
national level. However, based on several local studies and INFC statistics on hygrophilous
forests, their area, at national level, was assessed to be equal to some 30.000 ha.
Poplar and willow hedgerows perform many important environmental (soil and water protection,
carbon sink), ecological (ecological corridors and biodiversity reservoirs) and socio-economic
functions (fuelwood production, fencing, cultural, historic and scenic value).
The identity of the Po Valley landscape is also tied to the tree rows of poplars and willows and
is connected with the traditional use of these species as a support for the vineyard cultivation
(piantata padana) and almost disappeared in the last half century due to the intensification of
agriculture. From this point of view, the rows of poplars and willows in the lowlands are one of
the few remaining elements of the traditional agricultural landscape.
3. Genetics, Conservation and Improvement
Report research and applications of technology in genetics, conservation and tree
improvement achieved by the following categories:
(a) Aigeiros section
(b) Leuce section
(c) Tacamahaca section
(d) Other sections
(d) Willows
The 'Research Unit for Intensive Wood Production' (CRA-PLF) still leads Populus
and Salix domestication programs in four programmatic areas:
conservation and evaluation of genetic resources;
controlled hybridization and development of varieties able to meet the requirements of
7the main industrial applications or which can be used for phytoremediation and
production of woody biomass for energy;
production of genetically modified plants by the insertion of useful characters of
agronomic and environmental interest;
clone identification and assisted selection within conventional breeding programmes
using molecular markers (SSR; AFLP).
Conservation programs of Salicaceae are still active in order to maintain a broad genetic base
to support both long and short term breeding strategies and to select groups of fast growing
clones with a diversified genetic background. The genetic variability of the material cultivated
is extremely important to avoid epidemiological risks both in traditional plantations (wood
production for the plywood industry) and in the case of dedicated energy crops (biomass
plantations for the production of energy).
Conservation involves both in situ efforts (identification, cataloguing, assessment, and
protection of native populations) and ex situ (long-term storage of seed and pollen and the
preservation of wild collections in cultivated archives and arboreta). The CRA-PLF is
presently maintaining wide collections of poplar (around 1700 accessions) and willow (around
600 accessions). In particular the conservation of native Populus genetic resources (P. nigra,
P. alba) is extremely important as it ensures the ability of the species to adapt to future
changes in climate, pathogens, and hydrologic conditions. Moreover, stocks of these species
can be successfully used for phytoremediation and restoration of degraded sites and fluvial
areas.
Collections of seed lots and vegetative materials have been established recently in order to
enlarge the germplasm banks of the native species; screenings and assessment are underway.
The construction of levees, dams, and revetments along many of the major rivers has reduced
the natural cycle of flooding, essential to the regeneration of Populus nigra and, with a
consequent reduction of genetic resources. For this Eurasian species the preservation of its
genetic diversity is a priority throughout Europe and a core-network dynamic gene
conservation units is being established within the Phase IV (2010-2014) of the EUFORGEN
programme (http://www.euforgen.org/.)
Inter-specific hybridization of the P. ×canadensis taxon and recurrent breeding of parental
species P. deltoides and P. nigra are central to the CRA-PLF breeding program. The P.
deltoides and P. nigra parents of highest general combining ability identified in the early
1990s are currently used in a short-period specific commercial breeding program. Emphasis
has been placed on suitability for both energy biomass plantations as well as veneer
plantations.
7 elite P. ×canadensis clones selected within the F1 populations obtained in the first stage of
the breeding program (polycross and common tester mating design carried out in the mid
1980s with P. deltoides and P. nigra genotypes) and already submitted to the National Poplar
Commission for testing, will be proposed for temporarily registration in the National Register
of Basic Forest Materials in 2012. These materials were also tested for adaptability to different
European environmental conditions: Application for Community Plant Variety Rights has been
filed for n. 5 clones: ‘Diva’, ‘Aleramo’, ‘Tucano’, ‘Imola’, ‘Orion’; the last two, which are
8very suitable for biomass production, in 2011 obtained from the NPC the authorization to be
temporarily commercialized for the next 10 years.
Currently the possibility to obtain an F2 population using P. ×canadensis selected F1
genotypes grouped in sub-populations according to their characteristics of resistance and
growth-rate is being investigated and, according to schedule, also a second cycle of intra-
specific P. deltoides and P. nigra breeding using a multiple population structure will be carried
out.
The breeding program on willow that started in the Nineties (controlled crosses with Salix
alba × Salix alba and open pollination of S. alba, S. jessoensis and S. matsudana) is still
underway; new crosses using as parental the best clones of S. alba selected within the
progenies have been started: growth-rate, tree form, tolerance to diseases and pests
(Asymmetrasca decedens) and physical features (fiber length, cellulose content) are considered
in selection for biomass production and for biofuel crops. Several plantations with different
planting densities (European model and American model) have been established in different
pedo-climatic conditions and are still being monitored.
Seedlot collections started from some gene conservation units established in the last decade on
the Po river with a pool of P. nigra genotypes selected within the Italian P. nigra reserves
(provenance region, rooting, adaptability, tree form and growth rate); according to the EU
Directive 1999/105/EC on the marketing of forest reproductive material (FRM), these
materials could be classified as “source identified”. According to the experimental data
recorded in several pilot trials carried out on the Po river since 2000, a restricted pool of P.
nigra genotypes characterized by growth performances similar to those of I-214 has been
selected for cultivation in fluvial areas with restrictions on intensive agriculture and on use of
poplar hybrids; a list of native P. nigra to be homologated for restoration activities has been
furthermore identified.
The main achievements in Italian poplar biotechnologies have been registered in the
framewrok of the Popit. Project. The production and selection of new poplar clones is achieved
by means of innovative breeding programs that allow to increase the frequency of useful genes
and groups of genes in parental populations. Most characters of economic interest (resistance
to adversities, rapid growth, stem and crown shape) can be improved with a careful use of
parents in breeding programs and by clonal selection of superior individuals. To this aim the
availability of genetic and genomic maps represents a wealth of knowledge to be exploited in
advanced breeding programs. With the genus Populus the genetic maps have been used with a
QTL approach to identify the genomic regions containing genes that control monogenic and
polygenic characters. Molecular markers which are closely associated with important adaptive
and agronomic traits could be used in breeding for early marker-assisted selection (MAS)
(Mohan et al., 1997; Collard et al., 2005).
A number of programs of genetic mapping have been conducted on the genus Populus and
have led to the realization of more than 20 maps (Cervera et al., 2004; Gaudet et al., 2007;
Markussen et al., 2007; Woolbright et al., 2008). The availability of the complete DNA
sequence of Populus trichocarpa makes it possible to align the genetic maps with the genomic
9sequence using SSR and SNP markers as a bridge. QTL mapping is the first step towards
identifying the regions of the genome that control the phenotypic expression of quantitative
traits. Knowledge about the genetic control of the main characters behind productivity in plants
is still limited compared to that on the physiology of these processes. Molecular-marker
assisted selection (MAS) is currently seen as an important resource to be applied to traditional
programs of hybridization of tree species aimed at improving the quantity and quality of
productions (Boerjan 2005).
The Research Unit for Intensive Wood Production (CRA-PLF) of Casale Monferrato (formerly
Poplar Research Institute - ISP) carries out research on poplars and willows, aimed at obtaining
fast-growing clones, adapted to different cultivation environments resistant to adversities,
which are capable of producing good quality wood. The breeding activity has hitherto led to
the creation of several poplar (68) and willow (4) clones of high technological value, tolerant
to the most common adversities and particularly suitable for cultivation in different
environmental conditions, some of which have also been protected by breeder’s right at
European level,
To improve the efficiency of poplar and willow breeding programs, new biotechnological
approaches have been adopted and new laboratories have been set up for activities that include,
beside in vitro cultivation techniques and genetic transformation, the use of methods of
molecular analysis. The activity carried out so far has already made it possible to develop
effective protocols for the characterization and molecular identification of different poplar
species and clones, while genetic transformation has been successfully applied to some
Populus nigra, P. alba and P. xcanadensis clones with the insertion of exogenous genes for
resistance to insects and broad-spectrum herbicides. In addition, a genotype of Populus
deltoides and one of Populus nigra showing differential behavior towards rusts, Marssonina
spp. and to the wholly aphid, were used as parents to obtain a new progeny. From such
progeny a population was selected for obtaining a genetic map of P. x canadensis using of SSR
markers.
The Dipartimento di Scienze dell’Ambiente Forestale e delle sue Risorse - DISAFRI
(Department of Forest Environment and Resources) of Viterbo University has gained
considerable experience in studying the genetics of natural populations of European native
poplar (P. nigra, P. alba) and in describing, phenotyping and in the genetic analysis of poplar
pedigree. A research program was started in the late eighties on the genetic evaluation of
native poplar germplasm. At presents DISAFRI’s collections comprise several genotypes of
white poplar from all over the country and about 1000 black poplar genotypes of Italian and
European provenance. In the collection, moreover, are maintained F1 and F2 crosses, and
backcrosses, constituted with parents of ‘contrasting’ origin, and intended for the study of
morphological and phenological characters in order to investigate the determinants at the base
of biomass productivity. DISAFRI has produced the genetic maps of white poplar and of black
poplar and is presently working at finding the QTLs (Quantitative Trait Loci) that code for
characters involved in biomass productivity. As regards abiotic stress work has been
undertaken on the study of tolerance to salt stress in poplar.
104. Forest Protection
Report on the incidence, scale and impacts of damage in poplars and willows by biotic and
abiotic agents:
(a) Biotic factors including insects, diseases and other animal pests and outline
economic aspects and success of control measures undertaken and damage
prevention in the future.
• Insects
• Situation
The poplar and willow borer (Cryptorhynchus lapathi L.) is confirmed as the most important
pest in Italian poplar cultivation, as each year an expense of about 1 million Euros (30 % of the
total cost of poplar protection) is made in order to prevent damages in young plantations and in
nurseries. This pest is highly injurious in SRF biomass stands too, where chemical control is
not technically feasible and economically sustainable.
Other «key» poplar pests in Italy are the large poplar borer (Saperda carcharias L.) and the
goat moth (Cossus cossus L.), which ruin 8 % of poplar trees with considerable economical
losses, since injured wood is not appreciated by the plywood industry.
An important threat to poplar cultivation in Italy is represented by the recent introduction, in a
restricted area of Central Italy (Caserta Province), of the American pest Megaplatypus mutatus
(Chapuis), which is able to attack a large number of broadleaf trees (including some valuable
productive species such as walnut, apple, hazel, poplar) causing severe damage to the trunks.
In fact, adults bore a lot of tunnels into the trunk where eggs are laid and young larvae live
feeding on a specific Ambrosia fungus. M. mutatus has not spread yet to other Italian districts.
However, investigations are ongoing to determine suitable control strategies (including the use
of semiochemicals) in order to reduce damage in the affected areas and to reduce the risk of
spreading.
Buprestid beetles, particularly Agrilus suvorovi populnaeus Schaefer and Melanophila picta
Pallas, attack young trees suffering from transplant stress or drought, causing weakening or
stem breakage. As usual, these pests caused severe damage to 1 year-old plantations during the
hot and dry summers of the period concerned. The poplar clear-wing moth (Paranthrene
tabaniformis Rott.) affected not only poplar nurseries (which is normal), but also young poplar
stands in the Central Po Valley. The Poplar twig borer (Gypsonoma aceriana Duponchel) is
always present at high population levels throughout the whole cultivation area and causes
severe damage to young trees in nurseries.
Among sap-sucking insect pests, the poplar woolly aphid (Phloeomyzus passerinii Signoret)
was the most injurious one, causing bark damage and death of trees when attacks were heavy
and prolonged. Infestations were recurrently recorded, mainly in moist areas along rivers of the
Central Po Valley. The incidence of this pest is markedly enhanced by the extensive cultivation
of highly susceptible clones in Italy. Intense attacks of the polyphagous leafhopper
11Asimmetrasca decedens Paoli were recorded in poplar and willow nurseries in Northern Italy,
and heavy damage was particularly suffered by Salix alba clones. The risk of virus or
phytoplasma transmission by the pest has to be investigated more thoroughly.
In the reported period, some outbreaks of defoliators occurred causing damage in poplar
stands, which underwent growth losses and general weakening. Massive attacks of Byctiscus
populi L. occurred in the Po Valley and general high population levels of Chrysomela populi
L. were recorded throughout the period.
• Present control strategies and future perspectives.
Cryptorhynchus lapathi is effectively controlled by stem spraying in 1-3 year-old poplar stands
during sprouting (end of March-beginning of April) or during winter dormancy. The treatment
is directed to kill young larvae living in the bark. Pyrethroid insecticides are very effective
both in winter and in spring sprayings, whilst organophosphates are more active in spring.
Heavy infestations are unlikely to occur when healthy nursery stock is used for transplanting.
Saperda carcharias is generally controlled by chemical spraying against young larvae (end of
May) only in young stands, as an alternative to localised treatments by insecticide injection
into the gallery. The latter is most commonly adopted in older stands. It is really useful to
favour predation by the great spotted woodpecker (Picoides major L.), which is an important
natural enemy of the pest, preventing the elimination of dead or broken trunks which are used
by the woodpecker for nesting.
At present, Megaplatypus mutatus is monitored in the colonized area. Mass trapping by
synthetic pheromones is highly desirable in a near future, but at present this is still under
experimentation. Phloeomyzus passerinii is controlled, at the beginning of infestation, by
mineral oil sprayings, added with organophosphate insecticides when colonies have already
spread over a large part of the trunk. In areas where the attacks of the pest are recurrent,
resistant clones are strongly recommended. Within the CRA–PLF genetic improvement
program of poplars, clonal resistance is tested in laboratory by artificial inoculation of cuttings.
Also parental (Populus nigra and P. deltoides) genotypes are tested, in view of a finalised
hybrid production program. A study on the chemical basis of resistance is currently being
carried out, that could lead to the settlement of a new resistance test methodology. Defoliators
can be controlled by Bacillus thuringiensis or IGR (Insect Growth Regulator) insecticides, but
non-selective chemicals are still widely sprayed in poplar stands. Transgenic poplars encoding
proteinase inhibitors or B. thuringiensis toxins, behaving as resistant towards defoliators, have
been produced. Protection of nurseries against C. lapathi, P. tabaniformis and Gypsonoma
aceriana Dup. is currently achieved by periodical organophosphate sprayings (at 15 days
intervals) in June-July.
Diseases
• Situation; Present control strategies and future perspectives
12As in the previous years, the climate conditions greatly influenced the phytosanitary situation
of Italian poplar plantations in the period 2008-2011 (Fig. 1). As in the periods 2000-2003 and
2004-2007, conspicuous droughts occurred, though this time much before the vegetative
season (i.e. March in 2008, May and June in 2009, April and May in 2011). This was
associated with a very irregular distribution of rainfall, far from the equinoctial pattern typical
of the Po Valley, especially in 2009 and 2011. In particular, in 2009 lack of rainfall in May and
June was recorded, which was only partially counterbalanced by a peak during the high
summer; in 2011 such lack of rainfall occurred even earlier (April and May) and was followed
by another similar period which substantially lasted from July to October, interposed by an
anomalous very high peak in June. In fact, in 2011 the total rainfall was highly under the
annual average (about 660 mm versus 750 mm), contrary to 2010 when the total rainfall was
much above the average (about 1030 mm).
Consequently, particularly in 2009 and 2011 large mortality occurred in young plantations,
while the dry summer conditions induced typical symptoms, with drastic thinning of the crown
and consequent reduction of the annual growth, difficulty of lignification of the young shoots
and reduction of reserve substances for the period of dormancy.
Weak attacks of Phomopsis spp., Cytospora spp. and Discosporium populeum, inducing bark
necroses, were observed on stressed plants soon after transplant. The incidence of
Discosporium populeum, a cortical parasite of endemic weakness in the Po areas, able to cause
the death of already weakened young plants, was still very low, in contrast with the high levels
recorded ten years ago. In the adult plantations stressed by water deficit, cortical necroses were
observed with a relatively low spread but with localized high severity. This physiological
disorder, also known as “trunk brown spot”, can considerably reduce the quality of wood. In
2009, possibly alarming isolations of Fusarium avenaceum were obtained from bark necroses
occurred in adult plantations of several clones (e.g. ‘BL Costanzo’, ‘I-214’, ‘Onda’, ‘Triplo’)
in the middle Po Valley, since this fungus is known as primary pathogen.
The incidence of the leaf spot blight caused by Marssonina brunnea, up to now a widespread
foliar disease connected with severe phylloptosis and loss of production, was remarkably
reduced during the last four years in spite of the assessed susceptibility of ‘I-214’, the most
cultivated clone in Italy (more than 80 % of poplar stands). In 2011, in particular, its incidence
rose to levels able to induce defoliation only at the end of September. This unusual trend may
have been related to the prolonged drought occurred just at the beginning of sprouting, which
had probably damaged conidial viability, and more generally to the repeated drought events
occurred in the last vegetative seasons that may have gradually reduced the inoculum density.
For several years the spring defoliation caused by Pollaccia elegans had not caused any
economical damage due to the limited spread of the so called “Canadian clones”. The disease
is present only in some small areas of the Po valley, where it maintains an endemic character.
Recently, some attempts at reintroducing some very productive “Canadian clones” (e.g. ‘302
San Giacomo’, ‘Adige’, ‘Boccalari’) in big farms are being successful, in spite of their well
known susceptibility to P. elegans, since they have been planted in small groups, widely
spaced, and separated by plantations made of resistant clones. Probably, in this specific context
the incidence of P. elegans remains at tolerable levels owing to the scattered inoculum target.
13As regards leaf rusts by Melampsora spp. (i.e. M. larici-populina and, to a lesser extent, M.
allii-populina), by now in Italy all the recognized groups of pathotypes, better known as
physiological races have been observed– except for race E2 – with a persisting predominance
of race E3 and the recorded introduction of races E4 and E5. Rusts are still a limiting factor
typical in nurseries rather than in plantations, since summer defoliations in nurseries cause an
impaired sprouting of nursery stock after transplant and a stronger predisposition versus
weakness parasites (e.g. D. populeum, Cytospora spp. and Phomopsis spp. among fungi and
Melanophila picta, Agrilus suvorovi among pests). Instead, the damage caused by rusts on
Short Rotation Forestry must be seen more in terms of stump survival and, in the long period,
of integrity of the coppice stand rather than in terms of quantitative losses of dry matter.
Among all recurring diseases, rusts are the most challenging ones versus clonal selection and
thus represent a limiting factor of genetic renewal.
The cortical necroses likely associated with bacterial infections (Erwinia s.l.) are still sporadically
observed in nurseries constituted with “Luisa Avanzo” (P. ×canadensis), “Raspalije”, “Beauprè”
or “Boelare” (P. ×generosa). The limited use of these clones in plantations allow a negligible
incidence of this adversity. The presence of the Poplar Mosaic Virus remains very low, also
considering the low amount (3% of the cultivated surface) of P. deltoides or susceptible hybrids in
nurseries and plantations. Eradication in the nursery, with a rapid elimination of symptomatic
plants, is the only method to prevent PMV epidemics.
The incidence of root rots by Rosellinia necatrix has not changed in the last four years, remaining
limited to already affected stands.
(b) Abiotic factors including winds, floods, droughts, pollution and others, and outline
economic aspects and success of control measures undertaken and damage
prevention in the future. (SEE ABOVE)
5. Harvesting and Utilization
Report on the application of new knowledge, technologies and techniques in:
(a) Harvesting of poplars and willows.
In any poplar logging the working system usually adopted is the Short Wood System. The main
operations executed are: felling, processing and loading of the material. Generally bunching and
extraction are not necessary while processing of the trees (which includes sorting logs for different
end uses) and loading for subsequent transport to factories take place on the felling site. Extraction
of whole trees, with or without branches, can also be done, with consequent processing of
commercial logs at the landing.
In relation to the implementation of the several field activities, three levels of mechanization can
be identified: traditional, advanced and fully mechanized. The first one is characterized by low
mechanization: use of chainsaws for felling and of agricultural tractors for processing. The second
type is defined by intermediate mechanization, it foresees the use of equipment that can carry out
various operations, for example a feller-buncher for felling, bunching and for the alignment of
trees. The third level implies even higher mechanization with combined machines, for example a
14harvester with feller-buncher-delimber-cross cutter which can perform all the operations necessary
for producing the final assortments. In yards of the last two types forwarders and skidders are also
very often used for the extraction and loading of material as well as big chippers for chipping top
ends and branchwood.
Currently the traditional method is the one most frequently used, although the adoption of
advanced and fully mechanized working methods has spread in recent years.
The possible further expansion of an advanced mechanization depends on the availability of highly
professional operators for fully exploiting the potentialities of the machines, and on the presence of
well-organized and well administered enterprises able to quickly react to any sudden poplar wood
market variation.
(b) Utilization of poplars and willows for various wood products:
Several new poplar clones (Populus nigra × P. deltoides hybrids), not yet registered, were
studied as to their physical characteristics and rotary cutting attitude, to identify the best ones
suitable to undergo further selection and to be proposed for registration. Each clone was tested
choosing the butt log for rotary cutting trials; when cross cutting the log, some wood samples
were collected at different tree heights to test basic density and total shrinkage. For each clone
plywood panels were produced and subjected to mechanical testing.
Testing (both physical and mechanical) was also done to evaluate the influence of the site on
the rotary cutting attitude of some clones. To this purpose, trees of the same six clones were
taken from two different poplar stands located in very different sites.
A large industrial group has recently decided to establish in Italy an OSB (Oriented Strand
Board) production line; this will be the first one of this kind in Italy and the first expressly set
up to use only poplar wood. The production should start before the end of 2012.
Some preliminary investigation was done to evaluate the possibility of obtaining an innovative
“poplar-brick” to realize wood walls. Tests are currently under way.
(c) Utilization of poplars and willows as a renewable source of energy (“bioenergy”).
The Agricultural Engineering Research Unit of the Agriculture Research Council (CRA-ING),
between 2008 and 2011 focused its research activity toward the development of technological
innovations in relation to harvest mechanization, storage improvement and logistic issues for
collecting and conferring the biomass to conversion plants. The harvesting phase might cover
50 % of production costs of poplar (Populus spp.) for energy plantation (Short-Rotation-
Coppices – SRC). Chip quality is crucial from the viewpoint of energy yield, storage, type of
power plant and market price formation. Good wood chips dimensional distribution and low
moisture are the key parameters for the proper combustion in apposite boilers.
Two different approaches are currently adopted: harvesting and chipping in one step or cutting
and chipping in two separated stages (stick harvest). In the first case, self-propelled forage
harvesters equipped with heads able to execute sequentially cutting, chipping and product
upload on tractor trailers are used. Early trials showed that, using the Claas Jaguar harvesters, a
reduced size of wood chips was obtained which produced unfavorable effects on storage.
Seeing this, CRA-ING designed and realized a new type of rotor, changing the number of
15knives and their cutting angle. The modifications allowed on the one hand to increase by 22 %
the operative working capacity and, on the other hand, to improve wood chip quality with an
increased percentage of chips of the higher size classes (+13.80% for the 12.5 - 25 mm class)
and a diminished percentage of chips of the lower, less valuable, class (-17.80% of wood chips
shorter than 12.5 mm).
Concerning the whole-plant harvesting system, where cutting and chipping are done at separate
stages, CRA ING set up an innovative system consisting of two machines: the first one is a cut-
windrower which, during the physiological dormant phase of the plants, cuts and releases the
trees along a windrow (parallel to the forward direction of the tractor), the second one is a
wood-chipper endowed with a pick up system for harvesting and chipping the windrowed
trees, which is done between the end of April and the first days of June, in the Italian climate.
With this solution plants are less affected by the biological processes of degradation (implying
a reduction of dry matter losses). The natural dehydration process during the storage phase
allows to obtain, in the subsequent step of chipping, a more stable product, less prone to
fermentation risks and with less soil compaction problems. Furthermore, confining storage to
the windrow and the use of forage harvester endowed with pick up system consent to harvest
the product directly in the interrow saving the problem of moving the biomass before chipping
and of keeping part of the field unproductive for storage use. Finally, the chance to delay the
work of heavier machines to a drier season appreciably reduces soil compaction.
Once the biomass has been harvested, one of the main problems is to adequately match
biomass supply and the demand of bio-energy plants through an appropriate storage strategy.
To this end, several experiments were conducted aimed to identify the suitable conditions for
natural storage in the open air in order to define the parameters of efficiency, economy and
functionality ensuring the supply of biofuel to farms in a continuous manner and with the
proper moisture content.
The third pillar of the bioenergy chain concerns the logistics of biomass supply to conversion
plants, a link connecting the agricultural production to the processing industry. Since also in
this sector mechanization plays an important role, from both an economic and an
environmental point of view, CRA-ING has carried out activities focused on the solution of
practical problems taking into account the evolution of agricultural policies. The OCM sugar
reform and the plans of agricultural conversion towards agro-energies undergone by the sugar
beet sector have allowed, for the first time in Italy, to follow and monitor the entire process of
industrial restructuring.
One of the companies involved in this process is going to build a 30 MW power plant to be
supplied with biomass produced from 7,000 ha of short rotation poplar plantations. CRA-ING,
in collaboration with the Powercrop company, within the National Research Project
SUSCACE (Scientific Support to Convert farmers into energy) collected the data concerning
the characteristics of plants in order to dimension the mechanization of harvesting and the
distribution of energy crops cultivations destined to supply the plant. The data collected were
entered into a database linked to the application “SW_SUSCACE_01”. The application
allowed to manage the logistics of harvesting and transportation of the product to the plant
taking into account the characteristics of machines, soil and climate and the agronomic
16parameters at harvesting.
6. Environmental Applications
Report on the application of new knowledge, technologies and techniques for cultivation of
poplars and willows for:
(a) Site and landscape improvement (bank stabilisation, combating desertification
and salinization, shelterbelts and windbreaks, soil rehabilitation, urban and
peri-urban forestry for climate modification etc).
The Kyoto Protocol promotes afforestation and reforestation in order to foster sustainable
development and recognizes to forests an important role as carbon sinks. River restoration
projects aiming at restoring riparian habitats can be considered as part of reforestation
activities. The CRA-PLF together with the Po River Fluvial Park and other river parks carried
out several pilot trials (on about 150 hectares) to convert areas dedicated to conventional crops
or intensive poplar cultivation into floodplain forests, and to recover degraded areas on the
upper part of the Po River basin.
The main aim of these projects was to restore floodplain forests for recreational purposes and
to actively contribute to the conservation of native poplar genetic resources, black poplar in
particular, by creating a network of artificial in-situ gene conservation units to support a
dynamic evolutionary process in a short time. For each trial, plantings and maintenance
practices were recorded, under the supervision of the CRA-PLF. Two cases set up in 1996
were compared: one (the Lanca di Rivarossa case) was located along an old meander to
recover a gravel quarry and to create a conservation buffer strip in an agricultural landscape;
the other one (the Bosco di Musolino case) was meant to create an open parkland for
recreational activities and touristic exploitation and to improve the environmental value of a
densely populated area subject to flooding. The two plantations were characterized
respectively by a major reduction of cultivation practices and, in the second case, by the
application of intensive cultivation techniques. A simplified CO2 balance was calculated
comparing the emissions generated during the cultural practices and the C fixed in the biomass
yielded to evaluate the sustainability of plantations.
The stands were established on sites with homogeneous soil characteristics: in both cases
growth and mortality were very similar. A little difference on the CO2 stored was caused by a
different species compositions that influenced the dry weight. The CO2 released due to cultural
practices only partially affected the total balance: in the Lanca di Rivarossa case few
operations released 2.23 t/ha equal to 3.5 % of the total CO2 stored; in the Bosco di Musolino
case, where to date weed control is necessary (due to the recreational activities connected to
the near town), the CO2 released reached 8.06 t/ha equal to 12.5 % of the total CO2 stored. In
any case these two stands resulted sustainable from the point of view of the CO2 balance.
(b) Phyto-remediation of polluted soil and water (buffer zones, contaminated sites, waste
water management/treatment etc).
17Phytoremediation is a cleanup technology suitable for a variety of organic and inorganic
pollutants. Poplar and willow are the most important woody species utilized in
phytoremediation and several experiments and field applications have demonstrated the
effectiveness of these trees in our Country.
Poplars have been found to be able to take up several heavy metals including cadmium copper
(Borghi et al. 2008), chromium (Gatti et al., 2011), and zinc (Di Baccio et al., 2009). Poplars
have been reported to be able of performing a bio-accumulation of cadmium almost double as
compared to willow clones tested in the same experiment. However, cadmium appeared mostly
confined to the root system (Zacchini et al., 2009). Detailed studies on localization of
xenobiotics in plant tissues (Cocozza, et al., 2008), can be of help in optimizing
phytoremediation decision making and practices.
An early screening of clones more suitable for phytoremediation purposes can increase the
potential of a successful phytoremediation. Biodiversity provide a wide choice of genotypes to
test and evaluate for remediation capacity. Cadmium tolerance and distribution in plant organs
was investigated in ten poplar clones obtained from different species, hybrids and genotypes
(Pietrini et al., 2010). The experiment recorded variability of cadmium distribution among
leaves, stem, and roots of the different clones, providing preliminary indications of candidate
poplars clones suitable for specific phytoremediation processes. Zacchini et al. (2009)
compared a total of 16 poplar and willow clones for phytoremediation capability, through a
hydroponic screening for cadmium tolerance, accumulation and translocation.
In studies conducted on numerous poplar clones, P. alba AL35, resulted the one best
combining a high metal-accumulating capacity and a significantly higher concentration of free
and conjugated putrescine. This indicates the possibility of identifying physiological markers
associated with metal accumulation capacity (Castiglione et al. 2009).
The interaction between microflora and plant roots should always be seen as an important
element for a successful phytoremediation. The microbiological analysis of the soil during
remediation provides information on ecosystem stability. De Paolis et al. (2010) observed
differences in bacterial populations in plots planted with Populus and Salix spp. as compared to
herbaceous control plots. Authors interpreted this signal as an index of ecosystem stability,
indicating that fast growing trees, are more effective than other vegetation coverage not only
for direct heavy metal contaminated lands remediation but also from an ecological point of
view.
The use of mycorrhization can be of help in supporting poplar phytoremediation of polluted
soils. Poplar can carry out ex planta phytoremediation as a result of extensive root systems
development and flourishing microbial association. Plant host response depends on the fungal
species. Lingua et al. (2008) studied the phytoextraction capacity of willow and poplar
associated with AM fungi.
Genetic manipulation of poplars such as P. alba and hybrids has been reported for
strengthening the remediative mechanisms through genetic manipulation and transgene
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